A single layer structure electroluminescence devices-based on poly(

p

-phenylene vinylene)with two kinds of electron injection electrodes of aluminum and calcium were fabricated

of which electroluminescence emission can be observed in normal lit room. An interesting experiment phenomenon was observed. EL spectrum band depends on metal electrode. The ratio of intensity of the peak at 550 nm to that of the peak at 510 nm is changed as a work function of metal electrode. The reason to the different ratio was analyzed as compared the precesses of electroluminescence with photoluminescence. It is more clear of physical processes of the linear relationship of current density and brightness by an analysis in mathematics.